Genes, Peoples and Languages by Luigi Luca Cavalli-Sforza, Penguin,
拢18.99 ISBN 071399486X
THERE are only three big questions in science, or so we are told. How does
consciousness arise from a tangled jungle of neurons? How did the Universe
begin? And where do we come from?
All are huge issues. But for popular pulling power, brains and big bangs
can鈥檛 match the third big question. Whether you鈥檙e a physicist, an engineer or
just trying to induce consciousness in a PC near you, discovering your distant
forebears has a unique appeal.
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For 55 years, pioneering population geneticist Luca Cavalli-Sforza has been
occupied with meeting the ancestors. And he shows no sign of letting up. This week
(see 鈥淎 few good men鈥�)
he鈥檚 a co-author on research showing that most European men are
descended from 10 founding fathers. And the week before last, he was he was involved in a study
(New Scientist, 4 November, p 16),
suggesting that humankind鈥檚 founding father emerged 70,000 years after our first
common maternal ancestor.
In his new book Genes, Peoples and Languages, the Italian-born
scientist, now at Stanford University in California, looks back at a career
that鈥檚 taken him all over the world investigating key questions about who we
are. How did people end up in certain places? What is culture? Does language
mark us out from our primate cousins? Why do we have different languages? Is
race a cultural construct or a hard scientific fact? And how can telephone
books, priests and Y chromosomes help in the quest to find answers.
To help find answers Cavalli-Sforza realised that he needed both genetics and
mathematics, at a time when such ideas were considered unfashionable. He learned
his number crunching in the 1950s at the University of Cambridge with one of the
field鈥檚 pioneers, R. A. Fisher, developing algorithms that could detect subtle
variations among large quantities of data. Tiny differences in DNA sequences can
reveal common ancestry. 鈥淚鈥檇 always liked the application of mathematics in
biology,鈥� he says. 鈥淕enetic drift intrigued me, but people were very
sceptical鈥攅ven Professor Fisher.鈥�
But DNA variations are only part of the story. Cavalli-Sforza says that
changes in languages, too, reveal much about ancestry, an idea put forward by
Charles Darwin, no less. To discover how modern humans moved across continents,
you can examine the spread of languages, even people鈥檚 names in different
regions. In 1786, in the Bengal Asiatic Society of Calcutta, the first ever
discussion of language families took place. It has been a hot topic ever
since.
Cavalli-Sforza has also had to make use of more unusual sources of data. To
trace the movement of people in Italy, for example, telephone books and priests
gave him his answers. Telephone books were used to establish the extent to which
people with the same surnames lived in common regions. Priests in these regions
were then asked to encourage churchgoers to give blood samples for genetic
analysis. And Cavalli-Sforza鈥檚 results showed that modern populations reflected
ancient patterns of settlement in Italy.
In China in the 1980s, he and the Chinese geneticist Duo Ruo Fu recruited
postal workers to understand migration and settlement patterns. Much of China鈥檚
population shares a core set of surnames, and postal workers have developed a
smart system of coding to recognise different families who might share the same
name. This system was used alongside blood samples to help establish the origins
of people in northern and southern China and Taiwan.
On an even grander scale, Cavalli-Sforza has attempted to track down the
spread of agriculture. Did knowledge of how to farm spread by word of mouth, or
did people take a farming culture with them as they migrated? Analysis of
genetic material suggests that for agriculture to take hold, people had to come
from farming stock rather than simply learn about it from the neighbours.
And at the more local level, Cavalli-Sforza highlights questions that have
still to find answers. There鈥檚 work to be done, he says, on the origins of
languages spoken in Burkina Faso. There鈥檚 no resolution yet to the debate on the
relationship between Celtic languages and culture. And more research is needed
in southern India on how long the ancient, pre-Dravidian language
survived.
Cavalli-Sforza鈥檚 ambitious dream was to collect, store and analyse DNA from
all of the world鈥檚 ethnic groups. But despite support from leading scientists
worldwide, his Human Genome Diversity Project never properly got off the ground.
Obstacles have included the difficulties in getting consent from people who gave
blood in remote regions, the refusal of some governments to allow DNA to be
exported, and critics who argued that the project gave nothing back to
communities that contributed to it.
Cavalli-Sforza recognises these problems, and condemns the practice of asking
for samples for one purpose, only to use that material for
different鈥攑ossibly commercial鈥攁pplications without asking for
additional consent. Such consent is absolutely necessary, he insists, and must
be obtained before research is published. And he is keen to see that any genetic
material collected for research remains in the public, not private domain.
鈥淲e鈥檙e very strict,鈥� he says. No commercial exploitation will take place,
though material will be available to 鈥渂ona fide researchers, not
产颈辞迟别肠丑苍辞濒辞驳测鈥�.
What about future plans? There鈥檚 more work on the ancient human genome, of
course. As he points out, the publication of the Y-chromosome work, alongside
the research on mitochondrial DNA, means that we now have two lines of ancestry
to follow. He鈥檒l still be tracking Eve and Adam and all their descendants for a
while.
Genes, Peoples and Languages is no dry text. It鈥檚 a thoroughly
readable account of some of the most fascinating ideas around.